Cable guide in a shift lever for bicycle gears

ABSTRACT

A shift lever is used to remotely operate the change of gear in a set of bicycle gears. The shift lever comprises a housing part and a cable winder with a cable guide which the bicycle user can operate in a winding rotational direction to wind a cable, or in a releasing rotational direction to release the cable. One end of the cable connects interactively with the cable winder, at least in one of the two rotational directions. The housing part has a bar with a guiding edge which together with the cable guide form a cable channel for the cable, from which the cable cannot deviate, if the cable winder is actuated in the releasing rotational directional this occurs if the other end of the cable is not pulled or taken up by the set of gears.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a shift mechanism for a set of bicycle gears inaccordance with the precharacterizing clause of claim 1.

European Patent Application EP 0 676 325 A2 has disclosed a twist gripshift for a bicycle, by means of which bicycle gears can be shiftedusing a Bowden line. The cable of the Bowden line is pulled into thehousing of the shift mechanism by means of a cable reel when the latteris twisted in a winding rotational direction, a tensile force acting onthe cable in the set of gears having to be overcome. The tensile forcekeeps the cable tensioned in the shift mechanism and in the Bowden line,for which reason the cable also rests on the cable reel when the cablereel is twisted in a releasing rotational direction, thereby releasingthe cable in the direction of the bicycle gears. FIGS. 3, 5 and 6 show,in particular, the path of the cable from its fastening on the cablereel to the point where it leaves the housing, where there is nosignificant guidance of the cable associated with the redirection of thecable. When the cable reel is twisted in the winding rotationaldirection, jamming can namely occur in the bicycle gears, as a result ofwhich the cable temporarily loses tension and, in the shift mechanism inparticular, can cause a build-up on the cable reel between the pointwhere the cable emerges from the housing and its end, this build-upcausing the cable to spread out in an arc in the housing and rise fromits proper position on the cable reel.

For the abovementioned case, the present invention provides guidance forthe cable between the cable reel and the exit from the housing,preventing the cable from moving away to any significant extent from itsposition in the tensioned state when it is relaxed through delays ingear changes in the set of gears. Since the cable is generally securedon the cable reel by means of a nipple, it can furthermore also happenthat when the cable is relaxed under the abovementioned conditions thenipple rises from its anchorage in the cable reel when the cable reel isrotated in the releasing rotational direction and causes jamming in theshift mechanism.

SUMMARY OF THE INVENTION

The invention has thus set itself the object of guiding a Bowden cable,which can be subjected essentially only to tension, in such a way on itsway between its fastening on a cable reel by means of a nipple and thepoint where it emerges from a housing part of the shift mechanism that,when the cable reel is operated in the releasing rotational direction,the cable does not move away from the position it occupies under tensileloading, especially when the nipple is firmly connected to the cablereel.

This object is achieved by the features in the characterizing part ofclaim 1. Refinements can be found in the subclaims. An exemplaryembodiment of a cable guide in a shift mechanism for bicycle gears isexplained with reference to two partial sections, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cable reel in a housing part with a cable and a bar onthe housing part;

FIG. 2 shows the bar in the housing part with a guiding edge for guidingthe cable, forming a cable channel in a cable guide of the cable reel;

FIG. 3 shows the cable channel shown in FIG. 1, formed by a hollowprofile on the bar in conjunction with the cable guide on the cable reelin a detail representation.

DESCRIPTION OF THE PREFERRED EMBODIMENT

If 1 denotes a housing part of a shift mechanism for bicycle gears, thehousing part 1 has arranged rotatably within it a cable reel 2, on whicha cable 3 is guided in a cable guide or groove 4, the cable 3 ending ina nipple 5, which is secured on the cable reel 2. The cable reel 2 canbe operated in a winding or pulling rotational direction A and areleasing rotational direction F, causing the shift elements in a set ofbicycle gears to change gear. The cable 3 is generally preloaded by aspring in the set of gears in such a way that it always assumes astraight-line position in accordance with the cable tension where it isnot guided by profiles or edges. However, since with some bicycle gearsthe spring acting on the cable 3 in the set of gears cannot pull saidcable in, particularly when the bicycle is not moving, since clutches orgearwheels cannot engage in one another when the set of gears is notrotating, a pressure is produced when the cable 3 is operated in thereleasing rotational direction F, this pressure being capable of liftingthe cable 3 out of its predetermined position on the cable reel 2 at theunguided points, especially in the shift mechanism. When the cable reel2 is operated in the winding rotational direction A, the nipple 5 istaken along by an abutment 6 and the cable 3 is tensioned. If, for theabove reasons, the cable 3 cannot be taken up by the gears when thecable reel 2 is operated in the releasing rotational direction, thenipple 5 could rise from the abutment 6 in the cable reel 2, leave itspredetermined place and cause jamming between the cable reel 2 and thehousing part 1. To prevent this, a holding device has been provided tohold the nipple 5 in the place allocated to it both in the windingrotational direction A and in the releasing rotational direction F, evenunder unfavorable shifting conditions in the set of gears. For thisreason, a catch 7 has been provided, this catch having a tooth 10 thatcomes to rest on the end face of the nipple 5 once the nipple 5 hasstruck the abutment 6. The nipple 5 is moved into this position duringthe fitting of the cable 3 simply by being pulled in between a bevel 12on the cable reel 2 and a contour 13 on the catch 7, allowing a tooth 10on the catch 7, which can bend resiliently about a bending cross section11, to snap in behind the end face of the nipple 5.

The housing part 1 has a bar 8 with a guiding edge 9 that follows thepath of the cable 3 at least in part and forms a cable channel 14 withthe cable guide 4, preventing the cable 3 from assuring an uncontrolledposition within the shift mechanism when the cable reel 2 is operated inthe rotational direction F for cable release. Preferably, the cablechannel 14 is formed at least at a critical point 16 of the cable path,namely where the cable 3 leaves the cable reel 2. On the contrary, thecable is pushed out of the housing part 1 and produces a pushing forcein the set of gears in addition to the tensile force of the spring,assisting the gear change in the set of gears.

I claim:
 1. A shift mechanism for remotely operating gear changes in aset of bicycle gears, the shift mechanism comprising: a housing part; acable reel having a cable groove, the cable reel rotatable in a pullingrotational direction for pulling the cable and a releasing rotationaldirection for releasing the cable, one end of the cable entering into adriving connection with the cable reel, at least in one of the pullingand releasing rotational directions; a bar extending from the housingpart to substantially cover the cable groove and having a guiding edge,the bar and the cable groove forming a cable channel configured suchthat the cable does not deviate when the cable reel is operated in thereleasing rotational direction if the other end of the cable is nottensioned or taken up by the set of gears.
 2. The shift mechanism asclaimed in claim 1, wherein the end of the cable has a nipple forestablishing the driving connection between the cable and the cable reelin the tangential direction in both pulling and releasing rotationaldirections.
 3. The shift mechanism as claimed in claim 2, wherein thenipple comes to rest against an abutment in the pulling rotationaldirection and against a tooth of a catch in the releasing rotationaldirection.
 4. The shift mechanism as claimed in claim 3, wherein thecatch has a contour that, together with a bevel on the cable reel, formsa funnel shape through which the nipple can be pulled into its fixedposition on an abutment and behind the tooth of the catch when the cableis being fitted.
 5. The shift mechanism as claimed in claim 3, whereinthe catch has a reduced bending cross section to assist the snap-fittingmovement.
 6. The shift mechanism as claimed in claim 1, wherein thecable channel is formed at least at a critical point of the cable path,where the cable leaves the cable reel.
 7. The shift mechanism as claimedin claim 1, wherein the guiding edge follows a curve determined bytests.
 8. The shift mechanism as claimed in claim 1, wherein the guidingedge of the bar has a curved profile.